When engineers talk about visual regression or website change monitoring, pixel-level diffing algorithms (like pixelmatch or Euclidean RGB distance) are usually the default solution. However, in real-world web environments, pixel-by-pixel comparisons fundamentally fail under normal user interactions and dynamic rendering conditions: Elastic Layout Shifts: A single 20px dynamic banner inserted at the top of a page pushes every subsequent DOM element down, causing 100% of the downst...